// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_DNS_MAPPED_HOST_RESOLVER_H_
#define NET_DNS_MAPPED_HOST_RESOLVER_H_

#include <memory>
#include <string>

#include "net/base/host_mapping_rules.h"
#include "net/base/net_export.h"
#include "net/dns/host_resolver.h"

namespace net {

// This class wraps an existing HostResolver instance, but modifies the
// request before passing it off to |impl|. This is different from
// MockHostResolver which does the remapping at the HostResolverProc
// layer, so it is able to preserve the effectiveness of the cache.
class NET_EXPORT MappedHostResolver : public HostResolver {
public:
    // Creates a MappedHostResolver that forwards all of its requests through
    // |impl|.
    explicit MappedHostResolver(std::unique_ptr<HostResolver> impl);
    ~MappedHostResolver() override;

    // Adds a rule to this mapper. The format of the rule can be one of:
    //
    //   "MAP" <hostname_pattern> <replacement_host> [":" <replacement_port>]
    //   "EXCLUDE" <hostname_pattern>
    //
    // The <replacement_host> can be either a hostname, or an IP address literal,
    // or "~NOTFOUND". If it is "~NOTFOUND" then all matched hostnames will fail
    // to be resolved with ERR_NAME_NOT_RESOLVED.
    //
    // Returns true if the rule was successfully parsed and added.
    bool AddRuleFromString(const std::string& rule_string)
    {
        return rules_.AddRuleFromString(rule_string);
    }

    // Takes a comma separated list of rules, and assigns them to this resolver.
    void SetRulesFromString(const std::string& rules_string)
    {
        rules_.SetRulesFromString(rules_string);
    }

    // HostResolver methods:
    int Resolve(const RequestInfo& info,
        RequestPriority priority,
        AddressList* addresses,
        const CompletionCallback& callback,
        RequestHandle* out_req,
        const BoundNetLog& net_log) override;
    int ResolveFromCache(const RequestInfo& info,
        AddressList* addresses,
        const BoundNetLog& net_log) override;
    void CancelRequest(RequestHandle req) override;
    void SetDnsClientEnabled(bool enabled) override;
    HostCache* GetHostCache() override;
    std::unique_ptr<base::Value> GetDnsConfigAsValue() const override;

private:
    // Modify the request |info| according to |rules_|. Returns either OK or
    // the network error code that the hostname's resolution mapped to.
    int ApplyRules(RequestInfo* info) const;

    std::unique_ptr<HostResolver> impl_;

    HostMappingRules rules_;
};

} // namespace net

#endif // NET_DNS_MAPPED_HOST_RESOLVER_H_
